This is what Dr Google says. Common levothyroxine side effects include heat intolerance, a fast heart rate, and diarrhea. Weight loss and hair changes are also possible.

I've had doctors tell me there is no connection to this and that med. That is not what others who are taking it say. I also have an underactive thyroid. Way low. But do not take anything for it. I took a homeopathic med for thyroid that the doc claimed I would have no problem. Not true. I did make the mistake of not weaning myself off it and lost tons of hair. When I read that my hair loss was because of my thyroid, I got some more meds and the hair loss stopped immediately. Then, I WEANED myself off it, and had no problem.

Google the side effects of beta blockers. And are you drinking water? It can affect heart beat if you are not drinking enough. I am still not getting 8 cups down but more than I did most of my life. It made a difference for me.